Lubricant



Q Patented Deall, 1945 2,390,491 wnmcm Harry '1. Bennett and Jerry R.Marshall, Tulsa, Okla, assignors to Mid-Continent Petroleum Corporation,Tulsa, Okla, a corporation of Delaware No Drawing. Application January30, 1942,

Serial No. 428,867

2 Claims. (Cl. 252-486) This invention relates to lubricants and moreparticularly to the problem of inhibiting foaming therein. Objectionablefoaming occurs when air is violently whipped into lubricants. Anordinary illustration of this condition appears in gear housings wherethe gears are only partially covered with oil so as to turn inan'oil-air sphere. Rapid rotation of the gears will then convert thelubricant into a foamy mass lacking the required lubricating properties.In addition to the various objections arising from insufficientlubrication, the volume of the lubricant is very greatly increased, andportions of the foam may be forcibly discharged from the housing.Therefore, excessive foaming may result in actual loss of valuablelubricant, while greatly impairing the lubricating value of thelubricant.

In commercial practice, the hazards and economic losses due to foaminglubricants are recognized as serious problems in this art, but itappears that such foaming has been regarded as an inevitable result ofviolently whipping air into the lubricant. The usual high gradelubricants, deliberately prepared to meet the special requirements forgear oils, are subject to'objectionable foaming. Our investigation ofthe prior lubricents in this art has failed to disclose any real Isolution of these specific problems.

The present invention is a result of special study I and developmentwork devoted to numerous conditions involved in this subject, the objectbeing to create the cooperative conditions essential to a complete andentirely feasible solution of the old problem. Actual tests have shownthat the in-- vention herein described will positively inhibit foamingin the lubricants. The tests show that we have successfully accomplishedthis outstanding result in a commercially feasible manner,

[ herein is intended to cover reactions which may result eitherin theformation of' true sulfonic .acids, sulfuric acid esters or both; itbeing understood that the nature of the resultant product dependslargely upon the conditions and the materials which enter into thereaction. Thus the term su1fonated" is used generically to describereaction products resulting from the use of sulfating and sulfonatingagents.

Various products may be employed. However, we prefer to use an ester ofsulfonated carboxylic acid such as the reaction product of the acylesters of ricinoleic acid or of oleic acid, an unsaturated carboxylicacid, or of 12 hydroxy-ste'aric acid or other carboxylic acidscontaining a double bond or hydroxyl group or both when reacted with anenergetic sulfonating agent as oleum, chlorosulfonic acid or sulfuricacid ester as butyl sulfuric acid in the presence of a group protectingagent as acetic anhydride. Various combinations of the above reagentsmay be used, or one may use other reagents known to the art.

However, the resulting product that is pref ferred is an acyl ester of asulfonated carboxylic acid having more than 10 carbon atoms in the acidgroup and containing not mOre than 12 car- 'bon atoms in the acyl group.Esterification may 7 be in the sulfo group, the carboxyl group, the

whipped into the lubricant. In actual practice,

we have found that the quantity of'the selected ester may be very small,for example, less than 1%. and preferably less than 0.1%, of thelubricant. We will hereinafter refer to a specific exfoaming in certainpetroleum oils which would that the invention is not limited to thepopular have otherwise been subjected to very excessive foaming.However, it is to be understood that similar results are obtainable whenthe foam inhibitors are incorporated in other lubricants, and

chine known as a Mix Master" having rotary Example 1 Volume of lubricantmm gg figafi Lubricating stock Before Alter 16 minto minagitationagitation utes utes i B. A. E. 140 extreme presc. c. c. c. c'. c. c. 0.

sure gear lubricant"... 500 1,000 980 850 Above lubricant containin0.05% (am inhibi or 600 540 500 e00 Example 2 v Volume oi agitated.Volume of mbncam mixture after settling Lubricating ntock Before Altermin- 60 minagitation agitation utes utes c. c. c. c. e. c. c. c. S. A.E. 60 aeroplane oil. 875 825 600 Above lubricant contsining 0.05% foaminhibitor 500 525 500 500 If desired the selected ester may be blendedwith a solvent in order to incorporate the ester in the oil. In suchcase the solvent may be an organic or an inorganic solvent and the oneselected would depend upon its solvent value in the ester of sulfonatedcarboxylic acid and also its solvent value in lubricating oil.

It was found that a-small quantity,,less than 10%, 0t amyl acetate hadthe desirable solvent properties and could be used as the solvent.However, the use of amyl acetate is given here only as a specificexample and is not intended to limit the use of solvents to thisspecific solvent, nor to this type of solvents, because other solventsknown to the art possess the same valuable solvent properties.

Finally, it was found that when water was present, as is often the caseinside of gear housings, caused by the condensation of moisture from theair, that the foaming tendency of the oil was not increased by thepresence of water when an acyl ester of sulfonated carboxylic acid isused' to reduce foam formation, butin some cases the action of the foamreducing agent is increased in the presence of very small amounts ofwater.

It is, however, not to be construed that any solvent is necessary sincean acyl ester of sulfonated carboxylic acid as indicated will act as afoam reducing agent in the absence of all sol vents. The solvent merelyfacilitates the incorporating of the foam-inhibiting agent in the oil.

We claim:

1. A lubricant comprising a petroleum lubricating oil wherein foaming isinhibited by an acctyl ester of a sulfonated rlcinoleic aciddisinhibitor consisting of an acetyl ester of sulfonated ricinoleicacid, the quantity of said ester being less than .1% of the lubricantbut suflicient to inhibit foaming of said lubricant.

HARRY T. BENNETT. JERRY R. MARSHAIL.

